Cannabis use and abuse has symptoms that affect behavior, physical, cognitive, and psychosocial aspects of a person’s life. Symptoms include agitation, bloodshot eyes, challenges in problem solving, and paranoia.[3]

Cannabis use is associated with comorbid mental health problems, such as mood and anxiety disorders, and discontinuing cannabis use is difficult for some users.[4] Psychiatric comorbidities are often present in dependent cannabis users including a range of personality disorders.[5]

The use of cannabis at a young age such as the teenage years, can have serious impacts on depression and anxiety in youth and later in life.[6] There is evidence that cannabis use during adolescence, at a time when the brain is still developing, may have deleterious effects on neural development and later cognitive functioning.[7] The brain is not completely developed until a person reaches the age range of 22-27. Excessive use of marijuana can cause harm to this development.[8] Based on annual survey data, 7% of high school seniors that smoke daily function at a lower rate in school than students that do not.[9] The sedating and anxiolytic properties of tetrahydrocannabinol (THC) in some users might make the use of cannabis an attempt to self-medicate personality or psychiatric disorders.[10]

Prolonged cannabis use produces both pharmacokinetic changes (how the drug is absorbed, distributed, metabolized, and excreted) and pharmacodynamic changes (how the drug interacts with target cells) to the body. These changes require the user to consume higher doses of the drug to achieve a common desirable effect (known as a higher tolerance), reinforcing the body’s metabolic systems for eliminating the drug more efficiently and further downregulating cannabinoid receptors in the brain.[11]

Cannabis users have shown decreased reactivity to dopamine, suggesting a possible link to a dampening of the reward system of the brain and an increase in negative emotion and addiction severity.[12]

Cannabis users can develop tolerance to the effects of THC. Tolerance to the behavioral and psychological effects of THC has been demonstrated in adolescent humans and animals.[13][14] The mechanisms that create this tolerance to THC are thought to involve changes in cannabinoid receptor function.[13]

According to the National Cannabis Prevention and Information Centre in Australia, a sign of cannabis dependence is that an individual spends noticeably more time than the average recreational user recovering from the use of or obtaining cannabis. For some, using cannabis becomes a substantial and disruptive part of an individual’s life and he or she may exhibit difficulties in meeting personal obligations or participating in important life activities, preferring to use cannabis instead. People who are cannabis dependent have the inability to stop or decrease using cannabis on their own.[15] One study has shown that between 2001-2002 and 2012-2013, the use of marijuanna in the US doubled.[16]

Cannabis dependence develops in about 9% of users, significantly less than that of heroin, cocaine, alcohol, and prescribed anxiolytics,[17] but slightly higher than that for psilocybin, mescaline, or LSD.[18] Of those who use cannabis daily, 10–20% develop dependence.[19]

Cannabis withdrawal symptoms can occur in one half of patients in treatment for cannabis use disorders. These symptoms include dysphoria (anxiety, irritability, depression, restlessness), disturbed sleep, gastrointestinal symptoms, and decreased appetite. Most symptoms begin during the first week of abstinence and resolve after a few weeks.[4] According to a study in the U.S., 12.1% of heavy cannabis users showed cannabis withdrawal as defined by the DSM-5, and this was associated with significant disability as well as mood, anxiety and personality disorders.[20]

Cannabis addiction is often due to prolonged and increasing use of the drug. Increasing the strength of the cannabis taken and an increasing use of more effective methods of delivery often increase the progression of cannabis dependency. It can also be caused by being prone to becoming addicted to substances, which can either be genetically or environmentally acquired.[21]

Certain factors are considered to heighten the risk of developing cannabis dependence and longitudinal studies over a number of years have enabled researchers to track aspects of social and psychological development concurrently with cannabis use. Increasing evidence is being shown for the elevation of associated problems by the frequency and age at which cannabis is used, with young and frequent users being at most risk.[22]

The main factors in Australia, for example, related to a heightened risk for developing problems with cannabis use include frequent use at a young age; personal maladjustment; emotional distress; poor parenting; school drop-out; affiliation with drug-using peers; moving away from home at an early age; daily cigarette smoking; and ready access to cannabis. The researchers concluded there is emerging evidence that positive experiences to early cannabis use are a significant predictor of late dependence and that genetic predisposition plays a role in the development of problematic use.[23]

A number of groups have been identified as being at greater risk of developing cannabis dependence and, in Australia, for example, have been found to include adolescent populations, Aboriginal and Torres Strait Islanders and people suffering from mental health conditions.[7]

Young people are at greater risk of developing cannabis dependence because of the association between early initiation into substance use and subsequent problems such as dependence, and the risks associated with using cannabis at a developmentally vulnerable age.[7]

In the 2013 revision for the DSM-5, DSM-IV abuse and dependence were combined into cannabis use disorder. The legal problems criterion (from cannabis abuse) has been removed, and the craving criterion was newly added, resulting in a total of 11 criteria. These are: hazardous use, social/interpersonal problems, neglected major roles, withdrawal, tolerance, used larger amounts/longer, repeated attempts to quit/control use, much time spent using, physical/psychological problems related to use, activities given up and craving. For a diagnosis of DSM-5 cannabis use disorder, at least 2 of these criteria need to be present in the last 12 month period. Additionally, three severity levels have been defined: mild (2-3 criteria), moderate (4-5 criteria) and severe (six or more criteria) cannabis use disorder.[26]

As a time and cost saving alternative to extensive diagnostic interviews, several short scales for the screening for cannabis-related problems have been developed. Among the most frequently used screeners are the Cannabis Use Disorders Identification Test (CUDIT), Severity of Dependence Scale (SDS), Cannabis Abuse Screening Test (CAST) and Problematic Use of Marijuana (PUM).[27]

Clinicians differentiate between casual users who have difficulty with drug screens, and daily heavy users, to a chronic user who uses multiple times a day.[10] In the US, as of 2013[update], cannabis is the most commonly identified illicit substance used by people admitted to treatment facilities.[19] Demand for treatment for cannabis use disorder increased internationally between 1995 and 2002.[28] In the United States, the average adult who seeks treatment has consumed cannabis for over 10 years almost daily and has attempted to quit six or more times.[18]

No medications have been found effective for cannabis dependence as of 2019,[29] but psychotherapeutic models hold promise.[4]

Treatment options for cannabis dependence are far fewer than for opiate or alcohol dependence. Most treatment falls into the categories of psychological or psychotherapeutic, intervention, pharmacological intervention or treatment through peer support and environmental approaches.[23] Screening and brief intervention sessions can be given in a variety of settings, particularly at doctor’s offices, which is of importance as most cannabis users seeking help will do so from their general practitioner rather than a drug treatment service agency.[30]

The most commonly accessed forms of treatment in Australia are 12-step programmes, physicians, rehabilitation programmes, and detox services, with inpatient and outpatient services equally accessed.[31] In the EU approximately 20% of all primary admissions and 29% of all new drug clients in 2005, had primary cannabis problems. And in all countries that reported data between 1999–2005 the number of people seeking treatment for cannabis use increased.[32]

As of 2012, there is no medication that has been proven effective for treating cannabis use disorder; research is focused on three treatment approaches: agonist substitution, antagonist, and modulation of other neurotransmitter systems.[4] More broadly, the goal of medication therapy for cannabis use disorder centers around targeting the stages of the addiction: acute intoxication/binge, withdrawal/negative affect, and preoccupation/anticipation.[34]

For the treatment of the withdrawal/negative affect symptom domain of cannabis use disorder, medications may work by alleviating restlessness, irritable or depressed mood, anxiety, and insomnia.[35]Bupropion, which is a norepinephrine–dopamine reuptake inhibitor, has been studied for the treatment of withdrawal with largely poor results.[35]Atomoxetine has also shown poor results, and is as a norepinephrine reuptake inhibitor, though it does increase the release of dopamine through downstream effects in the prefrontal cortex (an area of the brain responsible for planning complex tasks and behavior).[35]Venlafaxine, a serotonin–norepinephrine reuptake inhibitor, has also been studied for cannabis use disorder, with the thought that the serotonergic component may be useful for the depressed mood or anxious dimensions of the withdrawal symptom domain.[35] While venlafaxine has been shown to improve mood for people with cannabis use disorder, a clinical trial in this population actually found worse cannabis abstinence rates compared to placebo.[35] It’s worth noting that venlafaxine is sometimes poorly tolerated, and infrequent use or abrupt discontinuation of its use can lead to withdrawal symptoms from the medication itself, including irritability, dysphoria, and insomnia.[36] It is possible that venlafaxine use actually exacerbated cannabis withdrawal symptoms, leading people to use more cannabis than placebo to alleviate their discomfort.[35]Mirtazapine, which increases serotonin and norepinephrine, has also failed to improve abstinence rates in people with cannabis use disorder.[35]

People sometimes use cannabis to cope with their anxiety, and cannabis withdrawal can lead to symptoms of anxiety.[35]Buspirone, a serotonin 1A receptor (5-HT1A) agonist, has shown limited efficacy for treating anxiety in people with cannabis use disorder, though there may be better efficacy in males than in females.[35]Fluoxetine, a selective serotonin reuptake inhibitor, has failed to show efficacy in adolescents with both cannabis use disorder and depression.[35] SSRIs are a class of antidepressant drugs that are also used for the treatment of anxiety disorders, such as generalized anxiety disorder.[37]Vilazodone, which has both SSRI and 5-HT1A agonism properties, also failed to increase abstinence rates in people with cannabis use disorder.[35]

Studies of divalproex have found no significant benefit, though some studies have found mixed results.[35]Baclofen, a GABA-B receptor agonist and antispasmodic medication, has been found to reduce cravings but without a significant benefit towards preventing relapse or improving sleep.[35]Zolpidem, a GABA-A receptor agonist and “Z-hypnotic” medication, has shown some efficacy in treating insomnia due to cannabis withdrawal, though there is a potential for misuse.[35]Entacapone was well-tolerated and decreased cannabis cravings in a trial on a small number of patients.[4]Topiramate, an antiepileptic drug, has shown mixed results in adolescents, reducing the volume of cannabis consumption without significantly increasing abstinence, with somewhat poor tolerability.[35]Gabapentin, an indirect GABA modulator, has shown some preliminary benefit for reducing cravings and cannabis use.[35]

The agonist substitution approach is one that draws upon the analogy of the success of nicotine replacement therapy for nicotine addiction. Dronabinol, which is synthetic THC, has shown benefit in reducing cravings and other symptoms of withdrawal, though without preventing relapse or promoting abstinence.[35] Combination therapy with dronabinol and the alpha 2 adrenergic receptor agonist lofexidine have shown mixed results, with possible benefits towards reducing withdrawal symptoms.[35] However, overall, the combination of dronabinol and lofexidine is likely not effective for the treatment of cannabis use disorder.[35]Nabilone, a synthetic THC analogue, has shown benefits in reducing symptoms of withdrawal such as difficulty sleeping, and decreased overall cannabis use.[35] Despite its psychoactive effects, the slower onset of action and longer duration of action of nabilone make it less likely to be abused than cannabis itself, which makes nabilone a promising harm reduction strategy for the treatment of cannabis use disorder.[35] The combination of nabilone and zolpidem has been shown to decrease sleep-related and mood-related symptoms of cannabis withdrawal, in addition to decreasing cannabis use.[35]Nabiximols, a combined THC and cannabidiol (CBD) product that is formulated as an oral (buccal) spray, has been shown to improve withdrawal symptoms without improving abstinence rates.[35] Oral CBD has not shown efficacy in reducing the signs or symptoms of cannabis use, and likely has no benefit in cannabis use withdrawal symptoms.[35] The CB-1 receptor antagonist rimonabant has shown efficacy in reducing the effects of cannabis in users, but with a risk for serious psychiatric side effects.[35]

Naltrexone, a mu opioid receptor antagonist, has shown mixed results for cannabis use disorder—both increasing the subjective affects of cannabis when given acutely, but potentially decreasing the overall use of cannabis with chronic administration.[35]N-acetylcysteine (NAC) has shown some limited benefit in decreasing cannabis use in adolescents, though not with adults.[35]Lithium, a mood stabilizer, has shown mixed results for treating symptoms of cannabis withdrawal, but is likely ineffective.[35]Quetiapine, a second-generation antipsychotic, has been shown to treat cannabis withdrawal related insomnia and decreased appetite at the expense of exacerbating cravings.[35]Oxytocin, a neuropeptide that the body produces, has shown some benefit in reducing the use of cannabis when administered intranasally in combination with motivational enhancement therapy sessions, though the treatment effect did not persist between sessions.[35]

Research that looks at barriers to cannabis treatment frequently cites a lack of interest in treatment, lack of motivation and knowledge of treatment facilities, an overall lack of facilities, costs associated with treatment, difficulty meeting program eligibility criteria and transport difficulties.[dubious – discuss][38][39][40]

Cannabis is one of the most widely used drugs in the world. In the United States, between 42%[2] and 49%[41] of people have used cannabis, an estimated 9% of those who use cannabis develop dependence.[18][42][needs update] 34.8% of Australians aged 14 years and over have used cannabis one or more times in their life.[43] In the U.S., cannabis is the most commonly identified illicit substance used by people admitted to treatment facilities.[4] Most of these people were referred there by the criminal justice system. 16% of admittees either went on their own, or were referred by family or friends.[44]

In the European Union (data as available in 2018, information for individual countries was collected between 2012 and 2017), 26.3% of adults aged 15–64 used cannabis at least once in their lives, and 7.2% used cannabis in the last year. The highest prevalence of cannabis use among 15 to 64 years old in the EU was reported in France, with 41.4% having used cannabis at least once in their life, and 2.17% used cannabis daily or almost daily. Among young adults (15–34 years old), 14.1% used cannabis in the last year.[45]

Among adolescents (15–16 years old) in a European school based study (ESPAD), 16% of students have used cannabis at least once in their life, and 7% (boys: 8%, girls: 5%) of students had used cannabis in the last 30 days.[46]

Globally, 22.1 million people (0.3% of the worlds population) were estimated to suffer from cannabis dependence.[47]

A 2014 Cochrane Collaboration review did not find sufficient data to evaluate the effectiveness of any medication for cannabis use disorder, though the authors commented that most available therapies are likely ineffective.[42]

^ abcMcLaren, J, Mattick, R P., Cannabis in Australia Use, supply, harms, and responses Monograph series No. 57 Report prepared for: Drug Strategy Branch Australian Government Department of Health and Ageing. National Drug and Alcohol Research Centre University of New South Wales, Australia.

^ abCopeland J, Gerber S, Swift W (December 2004). Evidence-based answers to cannabis questions a review of the literature. National Drug and Alcohol Research Centre University of New South Wales, A report prepared for the Australian National Council on Drugs.

^Degenhardt L, Hall W, Lynskey M (2000). Cannabis use and mental health among Australian adults: Findings from the National Survey of Mental Health and Well-being, NDARC Technical Report No. 98. Sydney: National Drug and Alcohol Research Centre, University of New South Wales.